Technology

SPL High Gain Technology

SPL is constantly pushing analog signal processing to its limits by combining the best possible components with perfectly optimized circuit design. As our latest achieve- ment in this ongoing process, SPL‘s High Gain Series surpasses the hitherto accepted limits of audio signal processing and combines truly unparalleled analog sound quality with the control and convenience of digital units.

Together with the MMC1 multi-channel mastering console, the parametric equalizer PQ, both as recording or mastering version, was the ﬁrst product of SPL’s new High Gain Series. Further High Gain projects are in planning, including a microphone preampliﬁer and a compressor, although no availability projections can be made for these currently.

The PQ is a fully parametric, dual-channel 5-band equalizer. As with all SPL High Gain units, the PQ has an operating voltage of 120 V and is constructed with the best analog components available.

Power for sound: SPL SUPRA components

The central component of the PQ is a fundamentally new ampliﬁcation design: discrete, custom made Class A audio operational ampliﬁers which run on a 120 V operating voltage (+/- 60 V). This amounts to over three times the operating voltage found in most high quality audio gear (+/- 15-20 V) and about twice as much as the highest voltages used in the best units currently available.

This extremely high voltage allows the circuitry to process an astonishing dynamic range of ca. 150 dB and an amazing +34 dB of headroom, virtually eliminating overloading of individual ﬁlter stages—even when processing extremely high-level signals.

For the ﬁrst time, transistor circuits with such an impressive degree of stability and freedom from harmonic distortion can be realized. After the revival of tube units in the early ‘90s, we feel that the time may be ripe for a revival of the „transistor sound“ in the near future.

Additional construction features

All crucial resistors in the I/O and ﬁlter circuits are subject to ultra-tight tolerances of 0.001% to ensure clean and accurate ampliﬁer stage performance. All circuit board tracks are double-width (1 mm) and double-thickness (70 micrometers), guaranteeing stable high-gain operation with minimum resistivity. A separate grounding track is placed between signal track pairs, virtually eliminating crosstalk for maximum signal separation.

The individually switchable ﬁlter bands are self-contained on separate circuit boards. Contrary to most conventional equalizers, the bands are not summed via a central stage, so that the signal passes only through those ﬁlter stages which are activated.